1. THE FIELD OF THE INVENTION
This invention relates to snatch blocks and more particularly to that class fabricated from only two elements adapted to engage endless lines and bight-like fasteners.
2. DESCRIPTION OF THE PRIOR ART
The prior art abounds with hanks or snatch blocks. U.S. Pat. No. 90,113 issued May 18, 1869 to W. McKay et al teaches a pulley having one end thereof journalled to a scissor-like clamp and the other end thereof journable to another member of the scissor-like clamp when the scissor-like clamp is closed by pivoting about a pivot hinge located between the free ends of a pair of clamp elements. The other ends of a pair of clamp elements, when the scissor-like apparatus is closed, forms an opening useful to secure a bite-like element. This apparatus can engage an endless line which is adapted to wrap around the pulley and the bite when the scissor-like elements are opened. The disadvantage of this apparatus resides in the having to lock together the scissor-like elements by tightening a bolt passing through a pulley to which the pulley is journalled.
U.S. Pat. No. 218,691 issued on Aug. 19, 1879 to C. Spencer teaches a snatch-lock comprising a pair of plates each of which carries a pulley axle such that the plates are rotatable relative to one another. One end of each of the plates carry a semi-circular portion which forms a complete loop upon the plates being rotated relative to one another into a lock position. The other ends of the plates carry similar semi-circular portions which form an additional loop. An endless line may be carried by the groove in the pulley as well as a bight captured within the loop formed by the semi-circular portions of the device when closed into loop form. Means are provided for locking together the pair of plates into a position when the semi-circular plates define the hoop. The teachings of Spencer require three physical elements besides the axle to which the pulley is journalled and require a locking device to maintain the apparatus in a closed condition.
Both McKay et al and Spencer suffer the common deficiency of requiring costly components which must be accurately machined or fabricated, which easily wear out due to the requirement of having multiple mating surfaces that are required to be aligned in tight fits such that captured bight-like elements and endless lines do not easily become displaced from their captured positions.